1. Field of the Invention
The present invention generally relates to automobile wheels equipped with decorative overlays. More specifically, this invention relates to a wheel and overlay assembly, in which the overlay is configured to define essentially the entire external appearance of the assembly, including the size and shape of turbine openings formed in the wheel, to the extent that a single inexpensive wheel style can be adapted to accept multiple overlay configurations in order to achieve widely varying styling effects for use on different passenger vehicles.
2. Description of the Prior Art
Decorative overlays are widely used in the automotive industry to enhance the aesthetic appearance of wheels on passenger vehicles, including unadorned steel wheels and cast aluminum wheels, the latter being difficult and very cost ineffective to plate with chromium. Together, a wheel and its overlay determine the wheel assembly's structural integrity and the aesthetic outward appearance, both of which are necessary for successful application in the passenger vehicle industry. Traditionally, wheel and overlay assemblies generally have divided the functions of structural integrity and aesthetic appearance, such that each is addressed separately by either the wheel or the overlay. The wheel contributes the structural integrity, while the overlay covers a portion of the outboard surface of the wheel in order to contribute to the wheel's aesthetic appearance.
By addressing each issue separately, the resulting wheel and overlay assemblies are able to achieve a significant reduction in the overall cost of the wheel, since the structural and aesthetic functions of the assembly can be addressed more effectively than would be possible if one single member was used to achieve both goals. To achieve this advantage, overlays of the prior art have of ten been attached using an in-situ molding technique. Primarily, the in-situ molding of such overlays adhesively attaches the overlay to a wheel with a low density polymeric foaming material with inherent adhesive characteristics, as opposed to more traditional wheel covers that require mechanical attachment devices such as clips, fasteners and the like. In-situ molding processes also generally provide both noise reduction and an impact-resistant outer covering that protects the underlying wheel.
Examples of prior art patents directed to in-situ molding processes include U.S. Pat. Nos. 4,976,497 and 5,128,085 to Post et al. The methods disclosed by Post et al. necessitate the use of a wheel as one-half of a mold into which the foaming material is injected, such that the entire inboard surface of the overlay contacts the outboard face of the wheel and strictly conforms to the contours and structure of the wheel. To reduce the weight-to-volume ratio of an overlay whose outboard surface does not closely conform to that of its wheel, Post et al. teach the use of weight reducing molding inserts selectively placed in those regions where the gap between the outboard surfaces of the overlay and wheel are greatest. Furthermore, the method of Post et al. involves the use of a lower molding part on which the wheel is placed prior to the molding operation. The lower molding part is shown as having raised portions that extend through the turbine openings in the wheel, such that tapered openings in the overlays are formed at the turbine openings.
Significant drawbacks exist with in-situ molding processes of the type taught by Post et al. For example, the use of molding inserts complicates the molding operation and contributes additional cost to the manufacture of a wheel and overlay assembly. In addition, because of the in-situ molding process, the wheel to which the overlay is to be mounted must be transported, stored and used at the molding station, which greatly complicates the molding operation and the economics associated therewith. Furthermore, the in-situ process dictates that the inboard peripheral shapes of the tapered openings in the overlay be strictly limited to the exact shape of the turbine openings in the wheel in order to contain the foaming material as it is being injected into the mold. Consequently, the turbine openings of the wheel influence to a significant degree the overall appearance of the wheel, because the shape and number of turbine openings in the wheel dictate the shape and number of openings of the complementary overlay when molded in-situ.
Accordingly, while the use of a wheel as a molding tool member allows for a customized fit of an overlay to the wheel, such molding methods substantially limit the ability of an overlay to be molded to have substantially different designs than the underlying wheel. For instance, an overlay molded in-situ cannot be formed to have its inboard surface axially spaced from the outboard surface of the wheel since the interface between the molded material and outboard surface of the wheel is relied upon to adhesively attach the overlay to the wheel. Similarly, for the same reasons, the in-situ molding process does not permit an overlay to significantly alter the shape and number of turbine openings in the wheel and overlay assembly, and therefore the in-situ process presents some limitations concerning the ability of the assembly to have a configuration substantially different from that of the wheel. Particularly in the passenger vehicle industry where the appearance of the overlay is of extreme importance, such design limitations are significant drawbacks.
Consequently, use of an in-situ molding process necessarily requires the use of a large number of wheels whose styling and construction differ considerably in order to provide for different outward appearances. Since the cost of retooling production facilities for the wheel portion of each new wheel and overlay assembly is approximately about five to about eight times the cost of retooling the overlay portion, retooling only the overlay portion for each new design rather than both the overlay and wheel would significantly reduce the cost of producing overlay and wheel assemblies. Furthermore, because the outward appearance is likely to vary more often than the structural configuration of the wheel, it would be desirable if the overlay could have a greater influence on the outward appearance of a wheel and overlay assembly, such that a single standardized wheel design could be employed to achieve widely varying styling appearances.
Accordingly, what is needed is a wheel and overlay assembly in which the overlay is formed to have significantly different contours from that of the underlying wheel. The underlying wheel's construction would take into account only the structural integrity necessary for its various applications. That is, one standardized or generic wheel design would serve a number of different vehicle applications with the ultimate objective being one standard wheel for each standard rim size; this, significantly reduces the cost per vehicle yet provides the function of structural integrity. In particular, the overlay of such a wheel and overlay assembly would be required to have portions that significantly alter the outboard contour features as well as the shape of the turbine openings of the wheel, if necessary, and possibly the number of turbine openings visible on the outboard surface of the assembly, such that the configuration of the underlying standard wheel is substantially masked by the overlay and only the aesthetic features of the cover are associated with the specific model of the vehicle on which the overlay is used. In this manner, the overlay would fully define the external appearance of the wheel and overlay assembly, rather than being limited to the outward appearance of the underlying wheel. As such, wheel and overlay assemblies could be produced having drastically different appearances by modifying only the overlay, rather than necessitating a completely new wheel design for each specific vehicle model.